OBJECTIVES: Economic evaluations of diagnostic technologies are less well established than for therapeutic technologies. The objective of this study was to undertake a cost-effectiveness analysis in German office-based centres of diagnostic strategies with and without DaTSCAN (123I-FP-CIT) SPECT imaging for patients with clinically uncertain Parkinsonian syndromes (PS) to distinguish between PS and essential tremor (ET), one of the conditions most commonly misdiagnosed as Parkinson's Disease. We report initial analytic results based on office-based expert opinion. METHODS: A Markov model was developed to simulate the progression of a cohort of patients with clinically uncertain PS who are managed in an office-based centre based on clinical judgement alone or receiving DaTSCAN. Health states were defined in terms of therapy (PS, ET, none) and underlying conditions (PS, ET). The model estimated time on potentially beneficial therapy (PBT: eg. PS therapy for underlying PS) and patient management costs over 5 years. Model probability inputs were from published studies and treatment patterns/resource use from a panel of German neurologists. Unit costs were from official sources. The cost of a DaTSCAN test (agent plus administration) was €929. 40-60% cohort members were assumed to have underlying PS. DaTSCAN sensitivity and specificity were 95%/100% (institutional read) and 93%/97% (blinded read). RESULTS: At 50% underlying prevalence and in the absence of DaTSCAN, 25% of cohort members had PBT at the outset, rising to 60% at 6 months and 62% at 5 years. Using DaTSCAN, 99% of patients had PBT at the outset reducing to 79% at 5 years. DaTSCAN use generated an incremental 1.4 PB years per patient, and 5-year costs were €795 lower for the DaTSCAN group. CONCLUSION: Adding non-invasive imaging to the management of patients with clinically uncertain PS may be considered to be a cost-saving strategy with an increase in time on potentially beneficial therapy.